/Engine/Source/Editor/UnrealEd/Classes/Editor/EditorEngine.h
Does an explicit actor rename. In addition to changing the label this will also fix any soft references pointing to it
static void RenameExistingActor ( [AActor](API\Runtime\Engine\GameFramework\AActor) * Actor, const [FString](API\Runtime\Core\Containers\FString) & NewActorLabel, bool bMakeUnique )